THE SMALLER SEA-SHELLS 



177 



It is one of our largest shells, the picture being much 

 smaller than the real shell, and specimens have been 

 found which are fully six inches in length. Its color 

 is dull white, somewhat 

 tinged with brown. 

 Specimens may some- 

 times be picked up on the 

 mud-flats, at the time of 

 low tide. And right 

 here let me remind vou 

 what a boon to collectors 

 the ocean tides are. A 

 large strip ot land is fre- 

 quently laid bare, ena- 

 bling the seeker after 

 shells and other sea- 

 treasures to walk safely 

 where a few hours before 

 the waves had been tumbling over one another. 



The shell of this species is pear-shaped, and it 

 ends in a long canal, to the left of which is a deep, 

 funnel-shaped umbilicus. The spire is beautifully 

 crowned with circles of sharp horns, and about the 

 middle of the outer lip there is a large, pointed tooth. 



We now come to the Purples, which received this 

 name not because the shells are of a purple color 

 themselves, but because in olden time a purple dye 

 was prepared from the bodies of similar mollusks. 

 This was especially true of a small Murex, M. trun- 

 culus^ that lived in the Mediterranean Sea, and the 

 inhabitants of ancient Tyre were peculiarly skilful 

 in preparing the rich "Tyrian Dye." 



Fig. 167 



